# Probability-Based Forwarding Scheme with Boundary Optimization for C-V2X Multi-Hop Communication

## TL;DR

This paper introduces a new method to reduce message redundancy in vehicle communication systems by optimizing message forwarding near transmission boundaries.

## Contribution

The paper proposes two novel boundary-optimized probability-based forwarding schemes to reduce redundancy in vehicular multi-hop communication.

## Key findings

- The proposed schemes reduce multi-hop forwarding redundancy by up to 36.07% compared to non-optimized methods.
- The schemes improve single-hop packet delivery ratio by up to 11.83% in dense traffic conditions.
- Boundary optimization effectively utilizes forwarding nodes while minimizing conflicts in high-density environments.

## Abstract

The Internet of Vehicles (IoV) can transmit the status information of vehicles and roads through single-hop or multi-hop broadcast communication, which is a key technology for building intelligent transportation systems and enhancing road safety. However, in dense traffic environments, broadcasting Emergency messages via vehicles can easily trigger massive forwarding redundancy, leading to channel resource selection conflicts between vehicles and affecting the reliability of inter-vehicle communication. This paper analyzes the forwarding near the single-hop transmission radius boundary of the sending node in a probability-based inter-vehicle multi-hop forwarding scheme, pointing out the existence of the boundary forwarding redundancy problem. To address this problem, this paper proposes two probability-based schemes with boundary optimization: (1) By optimizing the forwarding probability distribution outside the transmission radius boundary of the sending node, the forwarding nodes outside the boundary can be effectively utilized while effectively reducing the forwarding redundancy they bring. (2) Additional forwarding backoff timers are allocated to nodes outside the transmission radius boundary of the sending node based on the distance to further reduce the forwarding redundancy outside the boundary. Experimental results show that, compared with the reference schemes without boundary forwarding probability optimization, the proposed schemes significantly reduce forwarding redundancy of Emergency messages while maintaining good single-hop and multi-hop transmission performance. When the reference transmission radius is 300 m and the vehicle density is 0.18 veh/m, compared with the probability-based forwarding scheme without boundary optimization, the proposed schemes (1) and (2) improve the single-hop packet delivery ratio by an average of about 5.41% and 11.83% and reduce the multi-hop forwarding ratio by about 18.07% and 36.07%, respectively.